Filter system with canister filter element

ABSTRACT

A filter system for a fluid, particularly a liquid filter, especially an oil filter for an internal combustion engine, having a receiving head, a cup-shaped housing releasably connectable to the receiving head, and a replaceable filter element disposed the cup-shaped housing, in which the filter element has a liquid-tight casing which is received in the interior of the cup-shaped housing.

BACKGROUND OF THE INVENTION

The present invention relates to a fluid filter, particularly a liquidfilter, especially an oil filter for an internal combustion engine,comprising a receiving head, a cup-shaped housing releasably connectableto the receiving head, and a replaceable filter element disposed in thecup-shaped housing.

Two major types of fluid filters, particularly oil filters for internalcombustion engines, are known in the art. The first major type comprisesso-called spin-on filters. A spin-on filter has a cup-shaped housing, afilter element non-releasably disposed therein, and a threaded endplate. The cup-shaped housing is made of metal, so that it can withstandthe pressure pulsation which occurs in the interior of the filter duringoperation of the internal combustion engine. The spin-on filter isscrewed onto a receiving flange, or directly onto the engine block ofthe internal combustion engine, and during servicing is completelyreplaced with a new spin-on filter. This has drawbacks, however,resulting from the material mix of the filter because a mixture ofplastics, paper, and metal must be disposed of, and material separationfor disposal is problematic.

The second major filter type comprises so-called oil modules in which afilter element is releasably disposed in a preferably cup-shaped housingand with the aid of this housing is likewise screwed onto a receivinghead located within the oil circuit. For servicing, only the metal-freefilter cartridge needs to be replaced, while the cup-shaped housing is alifetime component.

German Utility Model No. DE 200 04 31 U1 discloses a liquid filter witha bypass valve. A hollow cylindrical filter element is releasablydisposed within a cup-shaped housing, and the cup-shaped housing isscrewed onto a connection head. A support tube, which receives thebypass valve, is disposed concentrically within the interior of thefilter element. The drawback of this arrangement lies in the changing ofthe filter element. First, there is a risk of contamination of thedirect surroundings of the oil filter element because the oil-soakedfilter medium still contains a residual amount of oil, which may drip asthe filter element is replaced. In addition, the hands of the servicepersonnel may become soiled because they come into direct contact withthe oil-soaked filter element.

SUMMARY OF THE INVENTION

Accordingly, it is the object of the present invention to provide animproved fluid filter, especially one which is suitable for internalcombustion engine applications.

Another object of the invention is to provide a fluid filter that can bedisposed of without requiring separation of different materials.

A further object of the invention is to provide a fluid filter which issimple and clean to use.

It is also an object of the invention to provide a fluid filter whichoffers protection against pressure pulsations.

These and other objects are achieved in accordance with the presentinvention by providing a filter system for filtering a fluid comprisinga receiving head, a cup-shaped housing releasably connectable to saidreceiving head, and a replaceable filter element disposed in saidhousing, in which the filter element is provided with a liquid-tightcasing which is received in the interior of the cup-shaped housing.

The fluid filter system according to the invention, particularly aliquid filter, especially an oil filter for an internal combustionengine, has a cup-shaped housing, a replaceable filter element disposedtherein, and a receiving head, such that the cup-shaped housing isreleasably connectable to the receiving head. The filter element furtherhas a liquid-tight casing within the cup-shaped housing. Theliquid-tight casing is preferably made of a plastic material, which maybe blow molded or injection molded. The exterior shape resembles theinterior shape of the cup-shaped housing, i.e., here too, a cup shape ispreferred. This shape may be designed to fully contact the cup-shapedhousing, contact it only at a few points, or not contact it at all, butthe distance between the inner wall of the cup-shaped housing and theouter wall of the liquid-tight casing should be as small as possible.This has the positive effect that when the filter element is replaced,the liquid present within the filter element cannot escape, andcontamination of the environment is prevented. Soiling of the hands ofthe service personnel is also avoided because the outer shell of theliquid-tight casing is dry and clean. A further advantage compared tothe conventional oil modules is that soiling of the inner wall of thecup-shaped housing is also avoided because the inner wall of thecup-shaped housing does not come into contact with the circulating oil.

In accordance with one advantageous embodiment of the invention, thecup-shaped housing is capable of absorbing and counteracting operationaldiameter fluctuations of the liquid-tight casing. These operationaldiameter fluctuations may, for example, comprise a diameter increase asa result of temperature fluctuations. By matching the liquid-tightcasing to the cup-shaped housing it is possible to produce theliquid-tight casing with a thin wall thickness and to use an inexpensiveplastic, so that the manufacture of the filter element becomes morecost-effective, and the desired functions can nevertheless be fulfilled.The cup-shaped housing, on the other hand, can be made more robust usinga metal or plastic, so that it can absorb the diameter increase of theliquid-tight casing. The liquid-tight casing is supported against therobust cup-shaped housing, which as a lifetime component can have agreater wall thickness than the liquid-tight casing.

It is advantageous if the filter element comprises at least one hollowcylindrical filter bellows, which sealingly separates a liquid inletfrom a liquid outlet. To this end, the liquid-tight casing includes asupport for the radial outer contour of the filter bellows. The filterbellows may be constructed from a zigzag folded or wound filter medium,which may be made of filter paper or a synthetic nonwoven material.Because of the pressure pulsation during operation there is a risk thatthe filter bellows will collapse under certain circumstances. Tocounteract this, many hollow cylindrical filter elements have a supportmember within their interior diameter, but this does not eliminate therisk of an outward collapse. With this configuration, a radial expansionof the filter bellows as a result of pressure pulsations can be absorbedby the support within the liquid-tight casing. In combination with theabsorption of the diameter fluctuations of the liquid-tight casing bythe cup-shaped housing, the forces that occur can be transmitteddirectly to the cup-shaped housing via the liquid-tight casing. Theresult is a combination of ease of maintenance through clean servicingof the filter element, integration of the function of an externalsupport member for the filter bellows, and cost-effective design of theliquid-tight casing because certain functions influencing stability canbe assumed by the cup-shaped housing.

It is advantageous if the outer support is constructed ascircumferentially distributed support contours in the liquid-tightcasing. On the one hand, the support contours support the outer contourof the filter bellows against radially outwardly acting forces and, onthe other hand, the support contours transmit the absorbed forces to thecup-shaped housing.

In accordance with another embodiment of the invention, the supportcontours form discharge volumes between the filter bellows and theinside of the liquid-tight casing, such that the discharge volumescommunicate with the floor of the liquid-tight casing. As a result, theliquid cleaned by the filter bellows can flow through the dischargevolumes to the floor of the liquid-tight casing. Apart from theseadvantages, i.e., greater ease of maintenance and the function of anexternal support member, a third advantage is achieved, i.e., thepossibility of using the support member to receive and transfer aliquid.

In accordance with yet another advantageous embodiment of the invention,the liquid-tight casing has at least one active contour in the region ofone of the end faces, extending radially beyond the circumferentialdiameter. This active contour enables, for example, a precise radial andaxial association or positioning relative to the cup-shaped housing. Theactive contour also makes it possible to check whether a filter elementis inserted and whether the inserted filter element is suitable for thefilter system.

Advantageously, the active contour is designed to communicate with arecess in the cup-shaped housing. Because no liquid is present outsidethe filter element, the filter element can be easily inserted into thecup-shaped housing and axially and radially fixed without a special sealbeing required.

According to another advantageous embodiment of the inventive concept,an integral anti-drain membrane or back-flow check membrane is disposedin the region of the liquid inlet and outlet. This integral anti-drainmembrane functions as a normal anti-drain membrane in the inlet regionand, in addition, as an anti-drain valve in the outlet region. Duringoperation of the internal combustion engine the inlet and outlet areopen if the filter element is inserted. If the filter element isremoved, however, the integral anti-drain membrane prevents the contentof the filter element from flowing out of the inlet and/or outlet. Thisagain has a substantial advantage during servicing because the filterelement can be removed from the cup-shaped housing and disposed of at anangle to the horizontal without any leakage of the liquid contents whichremain in the filter element.

According to yet another embodiment of the invention, two hollowcylindrical filter bellows are arranged concentrically within theinterior of the liquid-tight casing. The filter bellows have a commonend disk on one end face, and each bellows has a separate end disk onthe other end face. The end disk is preferably made of a thermoplasticmaterial, and the filter bellows are connected to the end disk byadhesive bonding or fusion welding. The common end disk is preferablyannular in shape, so that a flow-through opening for the filtered liquidis formed concentrically in the interior of the inner filter bellows.The separate configuration of the two end disks on the opposite end faceof the two filter bellows makes it possible to realize filter bellowshaving differing axial lengths.

It is advantageous if the common end disk has spring member on the sideopposite the filter bellows to support the filter bellows against theinside of the floor of the liquid-tight casing. This makes it possibleto axially support and fix the filter bellows relative to theliquid-tight casing.

According to yet another advantageous embodiment of the invention, theseparate end disk of the outer filter bellows simultaneously forms atight seal for the liquid-tight casing, so that the radially outer rimof the end disk is tightly and non-releasably connected to theliquid-tight casing. This connection may, for example, be provided bywelding, bonding or some other conventional process for permanentlyconnecting two plastic parts.

In addition, the separate end disk may advantageously have an annularcollar that extends axially away from the filter element. A seal memberto seal the filter element relative to the connection head is disposedwithin the annular collar. This seal member may, for example, be anO-ring or a sealing ring, which is disposed in a groove formed in theouter or inner circumference of the annular collar. Thus, the end diskof the outer filter bellows on the one hand secures the filter elementand on the other hand seals the filter element and provides a connectionto a connection head.

The liquid is filtered as follows. The unfiltered liquid flows throughat least one inlet into a gap between the two filter bellows. To filterthe liquid, it then passes through the two filter bellows—radiallyinwardly on the one hand and radially outwardly on the other. Thefiltered portion of the liquid stream that flowed inwardly into theinterior of the inner filter bellows then flows back into the liquidcircuit through the outlet. The filtered portion of the liquid thatflowed radially outwardly into the outer filter bellows is conducted tothe floor of the liquid-tight casing by the active contours of theliquid-tight casing, from where it flows through the opening in theseparate end disk to reach the interior of the inner filter bellows.From there it is likewise transferred back into the liquid systemthrough the outlet.

These and other features of preferred embodiments of the invention, inaddition to being set forth in the claims, are also disclosed in thespecification and/or the drawings, and the individual features each maybe implemented in embodiments of the invention either alone or in theform of subcombinations of two or more features and can be applied toother fields of use and may constitute advantageous, separatelyprotectable constructions for which protection is also claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described in further detail hereinafter withreference to illustrative preferred embodiments shown in theaccompanying drawing figures, in which:

FIG. 1 is a sectional view of a liquid filter according to theinvention;

FIG. 2 is a sectional view of the filter element and the cup-shapedhousing;

FIG. 3 is a perspective view of the filter element and the cup-shapedhousing;

FIG. 4 is a separate perspective view of the cup-shaped housing;

FIG. 5 is a sectional view of an outer shell of a filter elementaccording to the invention;

FIG. 6 is a perspective view of the anti-drain membrane;

FIG. 7 is a top view of a section in the region of the blocking member;

FIG. 8 is a sectional view of an alternative anti-drain membrane, and

FIG. 9 is a sectional view of a portion of an alternative filterelement.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

FIG. 1 is a sectional view of a liquid filter system 10 in which acup-shaped housing 11 is connected to a connection head by a bayonetconnection. The connection head 12 may be a separate connecting flange,or it may be formed directly from an internal combustion enginecomponent. The filter system is suitable for liquids of any kind used inan internal combustion engine, such as oils, fuels, hydraulic fluids, orcoolants. An inlet 13 and an outlet 14 are disposed in the connectionhead 12 of the filter system 10. The outlet 14 is arrangedconcentrically in the center of the connection between the cup-shapedhousing 11 and the connection head 12. The inlet 13 is distributedconcentrically around the outlet 14, also in the interior of theconnection between the cup-shaped housing 11 and the connection head 12.

Inside the cup-shaped housing 11 is a filter element 15. The filterelement 15 comprises a canister 16 which holds the filter medium ormedia. The circumference of the canister 16 is radially outwardlysupported against an inside wall 17 of the cup-shaped housing 11. At thesame time the canister supports an outer wall 18 of a first filterbellows 19 via grooves formed in the canister 16. The canister 16 isliquid-tight and additionally functions as an outer support tube for thefirst filter bellows 19 and a support against pressure pulsations at thecup-shaped housing 11. As a result, the canister 16 can be constructedrelatively thin with regard to its material thickness because the actualsupport against each pressure pulsation is provided by the cup-shapedhousing 11.

Disposed concentrically within the interior of the filter element is asupport tube 20 around which extends a second filter bellows 21. Thefirst and second filter bellows may be a zigzag folded filter medium, awound filter medium, a combination thereof, or some other conventionalfilter bellows. In the region of a housing floor 22 of the canister 16,the two filter bellows are held by an end disk 23, which is ring-shapedwith a concentrically disposed opening 24. A spring element 25 isintegrally formed on the end disk 23. Spring element 25 supports thefilter bellows against the housing floor 22 and axially locates andfixes the filter bellows by applying an axial spring force in an upwarddirection. Radial location and fixation is achieved by the inner contourof the canister 16.

At the opposite end of the filter bellows, the first filter bellows 19has an end disk seal 26. The second filter bellows 21, which is disposedin the interior of the first filter bellows 19, extends slightly higherin the axial direction than the first filter bellows 19. The end faceseal of the second filter bellows 21 is provided by an end disk 27,which is annular in shape and has a concentric passage for the outlet14. The end disk 27 has a coupling contour 28 extending axially towardthe connection head 12 for an anti-drain membrane 29. This couplingcontour 28 is distributed across the end disk 27 and comprises aplurality of pins or mushroom-shaped contours protruding axially towardthe connection head 12. The anti-drain membrane 29 is tightly coupled tothe end disk 27 by the coupling contour 28. It seals the liquid inlet 13when the internal combustion engine is stopped and the liquid outlet 14during servicing. The anti-drain membrane 29 is preferably made of asoft thermoplastic material, such as a thermoplastic elastomer (TPE).

The end disk 26 comprises a concentric, axially protruding annularcollar 30 with a groove in its outer circumference to accommodate asealing ring 31. When the cup-shaped housing 11 is connected to theconnection head 12, the annular collar 30 is inserted into a collar seat32 of the connection head, so that the sealing ring 31 provides a sealbetween the annular collar 30 and the collar seat 32. Disposedconcentrically in the interior of the collar seat 32 is an outlet tube33, which extends into the opening of the end disk 27 and thereby opensthe anti-drain element of the anti-drain membrane 29 on the outlet side.To seal the unfiltered side from the filtered side, sealing is effectedradially between the anti-drain membrane 29 and the outlet tube 33,which is disposed in the connection head 12. To seal the filter element15 liquid tight, the canister 16 and the end disk 26 are non-releasablyand sealingly interconnected by a connecting contour 34, e.g., by fusionwelding or adhesive bonding.

To release the filter element for servicing and to connect it, thecup-shaped housing 11 has a tool-holding fixture 35 having, for example,a hexagon socket or a hexagon head. For servicing, a tool is applied atthis point to separate the cup-shaped housing 11 from the connectionhead 12, or to reconnect the two parts. The plurality ofcircumferentially spaced locking element parts 36 in the form of aradially outwardly protruding lug is shaped from the one axial end ofthe canister 16. These parts engage in recesses of the cup-shapedhousing and recesses within a locking contour of the cup-shaped housing11, which will be described with reference to the following figures. Thepart 36 of the locking elements of the canister 16 simultaneously servesas a connecting contour 34 relative to the end disk 26. The connectionhead 12 has guides 37 into which locking contours formed from the part36 of the locking elements of the canister 16 and from the cup-shapedhousing 11 can be inserted and in which they are guided.

Disposed in the outer region of the connection head 12 is at least oneblocking member 38, which prevents a connection between the cup-shapedhousing and the connection head 12 when no filter element 15 or a wrongfilter element is inserted. The blocking member 38 then engages in arecess 44 of the cup-shaped housing 11 and thereby prevents the bayonetconnection from closing. The function of the blocking member 38 isillustrated in FIG. 7.

The liquid to be filtered flows through the inlet 13 of the connectionhead 12 into a space 39 between the two filter bellows 19, 21, thenflows through the second or inner filter bellows 21 into a dischargechamber 40 located on the filtered side within the support tube 20. Fromthe discharge chamber 40 the filtered liquid flows back into the systemthrough the anti-drain membrane 29, which is opened by the outlet tube33, and through the outlet 14 located on the filtered side. Anotherportion of the unfiltered liquid flows radially outwardly from the space39 through the first or outer filter bellows 19 into a space on thecanister side, from whence it flows downwardly to the canister floor 22.From the canister floor the liquid can again be returned to the systemthrough the outlet 14 on the filtered side.

FIG. 2 illustrates the combination of the filter element 15 and thecup-shaped housing 11 in a sectional view. Components corresponding tothose depicted in FIG. 1 are identified by the same reference numerals.FIG. 2 shows that when the cup-shaped housing 11 and the filter element15 are released from the connection head 12, the anti-drain membrane 29returns to its original shape in the region of the outlet 14 on thefiltered side because the outlet tube 33 is no longer present, so thatthe anti-drain membrane prevents the liquid stored in the filter element15 from leaking out. Since the anti-drain membrane 29 is made of athermoplastic elastomer, the contour can generate a return force withinthe blocking membrane, which return force has the effect of producing atightly closed seal at the outlet.

FIG. 3 is a perspective view of the cup-shaped housing 11 and the filterelement 15 disposed therein. Parts corresponding to those depicted inthe previous figures are identified by the same reference numerals. Thisfigure clearly shows the plurality of coupling contours 28 of the enddisk 27 for the anti-drain membrane 29. The open axial end of thecup-shaped housing 11 further has a plurality of regularly spacedlocking contours 42 around the circumference to produce the bayonetconnection within the filter system 10.

When the filter element 15 is correctly installed, the locking elementpart 36 on the filter element side is disposed in a recess 43 of thelocking contour 42 to complete the locking contour 42. If the filterelement 15 is not inserted, or if the filter element does not match, therecess 43 within the locking contour 42 remains free, so that theblocking member 38 prevents a bayonet-type connection between thecup-shaped housing 11 and the connection head 12. The blocking member 38then engages in the recess 43 and prevents the cup-shaped housing 11from being twisted relative to the connection head 12.

FIG. 4 shows a perspective view of the cup-shaped housing 11. To insertthe filter element 15, the cup-shaped housing 11 has circumferentiallyspaced recesses 44 extending axially from the open end of the cup-shapedhousing 11 and ending in the recesses 43 for the locking contour. Thefilter element 15 with the parts 36 of the locking elements is insertedinto the recesses 44 until it reaches the end of the recess 43 of thelocking contour so as to complete the locking contour 42. Only thiscompletes the locking contours 42 to establish the connection to theconnection head 12.

FIG. 5 is a sectional view of the canister 16, which represents theouter shell of the filter element 15. A plurality of grooves 45 aredistributed across the lateral face of the canister 16 and form asupport face 46 within the interior of the canister 16 for the firstfilter bellows 19. Because the grooves, 45 in the inner circumference ofthe canister 16 are not continuous, the filtered liquid flowing throughthe first filter bellows 19 can be easily fed to the discharge space 40on the filtered side via the canister floor 22.

The rest of the above-described filter element is then inserted into thecanister 16 and is connected to the canister 16 at the connectingcontour 34. This creates a liquid-tight system that preventscontamination of the surroundings and the environment and eliminates thehandling of dirty filters by the maintenance personnel during servicing.The axial seal of the canister 16 in the region of the open end is againformed by the locking element part 36, which engages in the recess .43of the locking contour 42 of the cup-shaped housing 11.

FIG. 6 is a perspective view of the anti-drain membrane 29. Componentscorresponding to those shown in the preceding figures are againidentified by the same reference numerals. The anti-drain membrane 29 issubstantially plate-shaped and is preferably made from a thermoplasticelastomer. Anti-drain membrane 29 has a plurality of openings 47 in theplate-shaped part to create the coupling with the end disk 27 via thecoupling contour 28. In its outer region, the anti-drain membrane 29 hasa sealing face 48 angled relative to the plate-shaped region for theinlet area of the filter system 10. Because of the flexibility of thematerial, the inlet area lifts from a sealing face in the end disk seal26 as the liquid to be filtered streams in and thereby ensures theinflow of the liquid. When the internal combustion engine is stopped,i.e., when there is no liquid pressure against the anti-drain membrane,the sealing face 48 seals the inlet 13 because of its elasticity.

Concentrically disposed in the interior of the anti-drain membrane 29 isa type of sealing valve 49 to seal the outlet when the filter element isremoved from the liquid circuit. The outlet seal 49 has a kind ofduckbill, which in the inserted state is opened from the connection head12 by the outlet tube 33 and which closes again because of its inherentelasticity when the outlet tube 33 is removed. Here, the anti-drainmembrane and the anti-drain valve are integrated in a single component.

FIG. 7 illustrates one possibility of using the blocking member 38. Onceagain, parts corresponding to those shown in the previous figures areidentified by the same reference numerals. FIG. 7 shows a top view of acutaway section in the area of the blocking member 38. The blockingmember 38 is disposed in the connection head 12. A locking pin 50 and aspring member 51 are disposed in the connection head 12 such that thelocking pin 50 is axially displaceable against the force of the springmember 51.

When the cup-shaped housing 11 and the locking head 12 are broughttogether and no filter element 15 is present or provided, the force ofthe spring 51 causes the locking pin 50 to engage in the recess of thelocking contour 43, thereby preventing the twisting necessary to createthe bayonet connection. If the filter element 15 is inserted correctly,the recesses 43 and 44 are filled by the locking element part 36 of thefilter element 15 and thereby complete the locking contour 42. As aresult, the locking pin 50 is pushed into the locking head 12 againstthe force of the spring member 51, so that the cup-shaped housing 11 canbe twisted relative to the connection head 12, allowing the bayonetconnection to be created.

FIG. 8 shows a sectional view of an alternative anti-drain membrane 29.Again, pars corresponding to those shown in the preceding figures areidentified by the same reference numerals. In this embodiment, theconnection to the filter element is realized in an alternative mannerthrough a circumferential annular groove 52 disposed concentrically tothe inlet sealing face 48. This annular groove receives an end disk (notshown). This connection is discussed further below with reference toFIG. 9.

FIG. 9 shows a sectional view of a portion of an alternative filterelement using the anti-drain membrane 29. Again, parts corresponding tothose shown in the preceding figures are identified by the samereference numerals. In this case, the inner filter bellows 21 issealingly connected by hot plate welding to the lower end disk 23 andthe upper end disk 27. A securing ring 53 holding the anti-drainmembrane 29 is concentrically disposed within the end disk seal 26. Thesecuring ring 53 is preferably integrally connected to the end disk seal26 via connecting webs 55, such that the connecting webs 55 arecircumferentially disposed around the outlet 14. The end disk seal 26and the end disk 23 each have sealing faces 54 for the outer filterbellows 19 and in addition fix the outer filter bellows. The canister 16(not shown) may be configured analogously to the preceding embodimentsand thus connects the two end disks 23 and 26.

The foregoing description and examples have been set forth merely toillustrate the invention and are not intended to be limiting. Sincemodifications of the described embodiments incorporating the spirit andsubstance of the invention may occur to persons skilled in the art, theinvention should be construed broadly to include all variations withinthe scope of the appended claims and equivalents thereof.

1. A filter system for filtering a fluid, said filter system comprisinga receiving head, a cup-shaped housing releasably connectable to saidreceiving head, and a replaceable filter element disposed in saidhousing, wherein the filter element is provided with a liquid-tightcasing which is received in the interior of the cup-shaped housing.
 2. Afilter system according to claim 1, wherein said filter is a liquidfilter.
 3. A filter system according to claim 2, wherein said filter isan oil filter for lubricating oil of an internal combustion engine.
 4. Afilter system according to claim 1, wherein the liquid-tight casing hassubstantially the same outer contour as the inner contour of thecup-shaped housing, such that the cup-shaped housing can absorb andcounteract operational diameter fluctuations of the liquid-tight casing.5. A filter element for a filter system comprising a receiving head anda cup-shaped housing releasably connectable to said receiving head forreceiving the filter element therein, said filter element comprising aliquid-tight casing in which is disposed at least one hollow cylindricalfilter bellows, which sealingly separates a liquid inlet from a liquidoutlet, and said casing having at least one support for supporting aradial outer contour of the filter bellows.
 6. A filter elementaccording to claim 5, wherein said at least one support comprisessupport contours distributed around the circumference of the casing suchthat the support contours both support the outer contour of the filterbellows against radially outwardly acting forces and transmit absorbedforces to the cup-shaped housing.
 7. A filter element according to claim6, wherein the support contours form discharge volumes that communicatewith the bottom of the liquid-tight casing such that liquid filteredthrough the filter bellows can flow through said discharge volumes to alowermost surface of the liquid-tight casing.
 8. A filter elementaccording to claim 5, wherein at least one active contour extendingradially outwardly beyond the circumferential diameter of theliquid-tight casing is disposed in the vicinity of an axial end face ofthe filter element.
 9. A filter element according to claim 8, whereinthe active contour engages in a recess of the cup-shaped housing.
 10. Afilter element according to claim 5, further comprising an integralanti-drain membrane disposed adjacent the liquid inlet and outlet suchthat the anti-drain membrane closes the inlet and outlet to preventegress of liquid from within the filter element when the filter elementis removed from the housing.
 11. A filter element according to claim 5,wherein two hollow cylindrical filter bellows are disposedconcentrically in the interior of the liquid-tight casing such that thetwo filter bellows have a common end disk at one axial end face, andeach filter bellows has a separate end disk at its opposite axial endface.
 12. A filter element according to claim 11, wherein the common enddisk on its side opposite the filter bellows has a spring member forsupporting the end disk and bellows against an inside surface of saidliquid-tight casing.
 13. A filter element according to claim 11, whereinthe separate end disk of the outer filter bellows simultaneously sealsthe liquid-tight casing, such that the radially outward rim of the enddisk is non-releasably connected to the liquid-tight casing to form aseal.
 14. A filter element according to claim 13, wherein the separateend disk has an annular collar extending axially away from the filterelement, and a seal member is disposed in the annular collar to seal thefilter element relative to the connection head.